[Qemu-devel] [PATCH v2] vmdk: fix metadata write regression

[Qemu-devel] [PATCH v2] vmdk: fix metadata write regression

[Reda Sallahi]

Commit "cdeaf1f vmdk: add bdrv_co_write_zeroes" causes a regression on
writes. It writes metadata after every write instead of doing it only once
for each cluster.

vmdk_pwritev() writes metadata whenever m_data is set as valid so this patch
sets m_data as valid only when we have a new cluster which hasn't been
allocated before or a zero grain.

Signed-off-by: Reda Sallahi <fullmanet@gmail.com>
---
v2: Corrected the commit id referenced in the commit message.

 block/vmdk.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index d73f431..1cbd487 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1202,13 +1202,6 @@ static int get_cluster_offset(BlockDriverState *bs,
     l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size;
     cluster_sector = le32_to_cpu(l2_table[l2_index]);
 
-    if (m_data) {
-        m_data->valid = 1;
-        m_data->l1_index = l1_index;
-        m_data->l2_index = l2_index;
-        m_data->l2_offset = l2_offset;
-        m_data->l2_cache_entry = &l2_table[l2_index];
-    }
     if (extent->has_zero_grain && cluster_sector == VMDK_GTE_ZEROED) {
         zeroed = true;
     }
@@ -1231,6 +1224,13 @@ static int get_cluster_offset(BlockDriverState *bs,
         if (ret) {
             return ret;
         }
+        if (m_data) {
+            m_data->valid = 1;
+            m_data->l1_index = l1_index;
+            m_data->l2_index = l2_index;
+            m_data->l2_offset = l2_offset;
+            m_data->l2_cache_entry = &l2_table[l2_index];
+        }
     }
     *cluster_offset = cluster_sector << BDRV_SECTOR_BITS;
     return VMDK_OK;
-- 
2.9.0

Re: [Qemu-devel] [PATCH v2] vmdk: fix metadata write regression

[Fam Zheng]

On Thu, 07/07 10:42, Reda Sallahi wrote:
> Commit "cdeaf1f vmdk: add bdrv_co_write_zeroes" causes a regression on
> writes. It writes metadata after every write instead of doing it only once
> for each cluster.
> 
> vmdk_pwritev() writes metadata whenever m_data is set as valid so this patch
> sets m_data as valid only when we have a new cluster which hasn't been
> allocated before or a zero grain.
> 
> Signed-off-by: Reda Sallahi <fullmanet@gmail.com>
> ---
> v2: Corrected the commit id referenced in the commit message.
> 
>  block/vmdk.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index d73f431..1cbd487 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1202,13 +1202,6 @@ static int get_cluster_offset(BlockDriverState *bs,
>      l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size;
>      cluster_sector = le32_to_cpu(l2_table[l2_index]);
>  
> -    if (m_data) {
> -        m_data->valid = 1;
> -        m_data->l1_index = l1_index;
> -        m_data->l2_index = l2_index;
> -        m_data->l2_offset = l2_offset;
> -        m_data->l2_cache_entry = &l2_table[l2_index];
> -    }
>      if (extent->has_zero_grain && cluster_sector == VMDK_GTE_ZEROED) {
>          zeroed = true;
>      }
> @@ -1231,6 +1224,13 @@ static int get_cluster_offset(BlockDriverState *bs,
>          if (ret) {
>              return ret;
>          }
> +        if (m_data) {
> +            m_data->valid = 1;
> +            m_data->l1_index = l1_index;
> +            m_data->l2_index = l2_index;
> +            m_data->l2_offset = l2_offset;
> +            m_data->l2_cache_entry = &l2_table[l2_index];
> +        }
>      }
>      *cluster_offset = cluster_sector << BDRV_SECTOR_BITS;
>      return VMDK_OK;
> -- 
> 2.9.0
> 

Looks good, nice catch!

Reviewed-by: Fam Zheng <famz@redhat.com>

Re: [Qemu-devel] [PATCH v2] vmdk: fix metadata write regression

[Max Reitz]

[-- Attachment #1: Type: text/plain, Size: 749 bytes --]

On 07.07.2016 10:42, Reda Sallahi wrote:
> Commit "cdeaf1f vmdk: add bdrv_co_write_zeroes" causes a regression on
> writes. It writes metadata after every write instead of doing it only once
> for each cluster.
> 
> vmdk_pwritev() writes metadata whenever m_data is set as valid so this patch
> sets m_data as valid only when we have a new cluster which hasn't been
> allocated before or a zero grain.
> 
> Signed-off-by: Reda Sallahi <fullmanet@gmail.com>
> ---
> v2: Corrected the commit id referenced in the commit message.
> 
>  block/vmdk.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)

Thanks Reda, I've applied the patch to my block branch:

https://github.com/XanClic/qemu/commits/block

Max


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 498 bytes --]